Thread: The D2a Diesel with never changing fuel economy

Would low compression show up as an imbalance on the nanocom?

Originally Posted by SiddersC

Would low compression show up as an imbalance on the nanocom?

it SHOULD, yes.

JC

When my car went in to the shop the diagnostics apparently didnt show any fault, only when the comp test was done did things get exxy?

How is a compression test done on a TD5? What do i need to test through the glow plugs? There is only four glow plugs. Is there an adapter to go through the fuel injection?

Depends on the setup of the engine, I've seen ports with screw in plugs that could be removed or you pull an injector. Either way you can't use a petrol type tester that you just hold in place. Funny when you see an apprentice do it though with a low pressure screw in and it explodes in his hand, then he gets another push in and compression blasts it out from under the bonnet. Only then he asks what's he doing wrong.

Originally Posted by Tombie

Try resetting the transmission adaptations each tank for a few and see what you get...

I was just thinking about this this evening. I have found when I go 4WDing in low range I generally get more km's out of the tank - i.e. the last time I went 4WDing for approximately 65km in low range. I achieved over 500kms from that tank of fuel which is around 50kms more than normal.

I wonder if the transmission adaptions are different for low range and that effected the fuel economy?

Originally Posted by twr7cx

I was just thinking about this this evening. I have found when I go 4WDing in low range I generally get more km's out of the tank - i.e. the last time I went 4WDing for approximately 65km in low range. I achieved over 500kms from that tank of fuel which is around 50kms more than normal.

I wonder if the transmission adaptions are different for low range and that effected the fuel economy?

The adaptions are basically to compensate for wear in the auto. There is a preset value for the time a shift should take to complete. The transmission ECU continually adjusts shift pressure to ensure shifts complete in the preset time. As the auto clutches wear the pressures are increased to keep shift times close to target values.

There are adaptations for three speed ranges, but I'm not sure that there is one specifically for low range. It shouldn't matter either way as the auto will adapt on the fly and new adaptations are learnt as required.

Reseting the adaptation basically removes the compensation for wear so you get the initial shifts taking longer than the target time. This is interpreted as smoother shifting because the auto is taking longer to complete each shift. The idea that resetting adaptations in the auto will fix problems is ultimately a myth.

cheers
Paul

Originally Posted by twr7cx

I was just thinking about this this evening. I have found when I go 4WDing in low range I generally get more km's out of the tank - i.e. the last time I went 4WDing for approximately 65km in low range. I achieved over 500kms from that tank of fuel which is around 50kms more than normal.

I wonder if the transmission adaptions are different for low range and that effected the fuel economy?

That´s what I´m trying to compare by looking at inputs from your car and others Disco Auto... Justfishing has already send me some fuellings. I´ll have a look. What seams to me is that you car revs to much before changing gear...